Examining bones to see what they reveal

Throughout human history our bodies have adapted over time to the conditions in which we live. Now scientists at the Pennsylvania State University Center for Quantitative Imaging are examining bones to see what they reveal, not only about our ancestors, but about our lifestyles and eating habits.


Throughout human history, our bodies have adapted over time to the conditions in which we live.

Now, scientists at the Pennsylvania State University Center for Quantitative Imaging are examining bones to see what they reveal, not only about our ancestors but our about our lifestyles and eating habits.

Here's the story.

About 12,000 years ago, agriculture and animal domestication emerged in Southwest Asia and Mesoamerica, but before that, foraging culture was the only sustainable lifestyle.

Hunter-gatherers has a variety of strategies they used to hunt and trap their prey, such as mammoths and bison.

Nowadays, to include bison in your diet, you can just head to your favorite burger spot and take a seat.

This change in lifestyle, over time, has also changed the very structure of our bodies, and at Penn State's Center for Quantitative Imaging, those changes are being studied.

My main research interests are in the variation in skeletal morphology in different primates and humans and the relationship of that variation in bone shape and form to behavior and other aspects of primate and human biology.

A lot of what our research is showing is that earlier hunter-gatherers, people who were more active, have much more bone, even at the same body size, so they are probably growing stronger skeletons because of the types of behaviors that they're engaging in.

As we moved into more sedentary lifestyles and moving into the present, more recent historical times, we have less bone, and the less bone you have as a young adult predisposes you, essentially, to potentially getting osteoporosis or having deleterious bone loss when you are older.

Learning more about these changes can lead to a better understanding of causes and solutions for modern-day diseases.

We'll be able to potentially provide a baseline of variation that will allow us to then compare what modern people are doing and potentially come up with some preventive mechanisms for increased activity, better diets, and other intervention-type approaches that would help alleviate some of the stress on the medical system that osteoporosis is posing.

To get a closer look at the bones they study, Tim and Lily use a specially designed micro-CT scanner.

So this is a computer tomography scanning system that allows us to nondestructively image the internal geometry and structure of objects, a variety of types of objects.

Primarily, we're interested in both biological questions, things like skull morphology and skeletal morphology in different animals.

In our lab, we're interested in bone morphology and how it changes over time and as well as between species and different populations of humans, specifically.

So with the CT scanner, we're able to look not only at the outer morphology but also on the inside, to get a little bit more detailed look at the variation between populations.

So, what's the difference between the X-rays this machine produces compared to the X-rays you get at the dentist?

Well, it's all about the resolution.

If you go to a hospital or to a doctor's office and get a medical CAT scan, what you're typically doing is seeing internal structure in your body at a certain resolution, approximately half a millimeter or a little bit less.

This scanner is capable of going down to submillimeter resolutions at the level of about 5 microns, all the way up to, maybe, about 200 or 300 microns.

The research shows how our bones have changed over the course of many centuries, but it also looks at differences between someone like me, a self-proclaimed carnivore, and my friend, the proud vegan.

It's been pretty clear that environmental loading has been a big impact on bone variation, but I'm really interested in seeing if there are other aspects that also influence it, like if there's sociocultural factors that make people choose to behave differently, and if their diet changes.

Dietary effects on bone are still not completely clear, and so one of the aspects of what we're looking at is if you have very different diets, what are the effects?

We used to say something about lifestyle and activity, and these images allow us to go even deeper, so we can see at a much finer scale some of the internal structure of bone that has not been accessible without destroying the bone until very recently.